Fixing structure between links and pins in crawler

ABSTRACT

A pressure receiving surface ( 8 ) having a diameter gradually decreasing in an axially inward direction is formed at an outer end portion of a pin ( 1 ), whereas a pressing portion ( 7 ) is formed at a circumferential edge of an opening of a pin insertion hole ( 5 ) of a link ( 2 ). A retaining ring ( 3 ) is formed with a friction surface ( 9 ) to be press-contacted to the pressure receiving surface ( 8 ) when a force is applied from the pressing portion ( 7 ) upon development of a relative movement in a disengaging direction. The retaining ring ( 3 ) and the pressure receiving surface ( 8 ) share a greater area of contact than in the prior art, providing sufficient friction. This makes possible to provide a fastening structure of the link and the pin of a crawler belt which can be assembled by simple operation at a low cost, without requiring a high machining accuracy, and thus can be manufactured at a low cost.

TECHNICAL FIELD

The present invention relates to a fastening structure between a linkand a pin of a crawler belt in a vehicle such as a construction machine.

BACKGROUND ART

A crawler belt utilized in a construction machine, such as a bulldozerand a hydraulic shoveling machine, comprises an endless annular linkchain provided with shoes (crawler shoes) for contact with ground. Thelink chain has such a structure that a plurality of links areinterconnected by pins. A structure of the link interconnection is shownin FIG. 8. As shown in this figure, the link chain includes apredetermined number of link pairs of a left-hand and a right-hand links31, 32 disposed in a longitudinal direction. In each of the link pairs31, 32, a pin 33 and a bushing 34 fasten an end portion of alongitudinally preceding link pair to a front portion of the followinglink pair. More specifically, the pin 33 is inserted into the bushing34, and the bushing 34 is press-fitted into rear holes 41 a, 42 a of thepreceding links 31 a, 32 a, whereas the pin 33 is press-fitted intofront holes 41 b, 42 b of the following links 31 b, 32 b. Since thebushing 34 and the pin 33 are pivotable, the preceding and the followinglinks 31 a, 31 b are connected with each other in a bendable manner likea joint. It should be noted here that, in FIG. 8, a portion indicated bynumeral 35 is a lubricating oil supplying hole. Lubricating oil suppliedhere provides lubrication between the pin 33 and the bushing 34.

According to the crawler belt described as above, the pin 33 issubjected to a large force in a direction of thrust during use.Therefore, according to the link chain described as above, a retainingmechanism for preventing the pin 33 from coming out of the links 31, 32is provided (for example, U.S. Pat. No. 4,618,190). According to thisfastening structure between link and pin, an annular recess is formedaround an opening of the pin insertion hole in the link. Further, closeto an end portion of the pin, a circumferential groove smoothlyrecessing in an axially inward direction is formed. The recess in thelink and the groove in the pin form a cavity having an annular opening,between the circumferential edge of the opening of the pin insertionhole and the outer end portion of the pin. Into this cavity, there isdriven an annular retainer made of a metal for preventing the pin fromcoming out. The retainer is plastically deformed to conform to the shapeof the cavity, so as to fill the cavity with the retainer, therebypreventing the pin from relative, disengaging movement out of the linktoward the side away from the opening.

Now, with the above described fastening structure between link and pin,in order to prevent development of an excessive play between the linkand the pin, the plastic deformation of the retainer must be carried outsufficiently so that the retainer is tightly fitted to conform to theshape of the annular cavity. However, in order to achieve this, there isa need for complex machining operation, and a high dimensional accuracyin the product. In addition, the recess of the link and the groove ofthe pin must be aligned with each other accurately, which leads aproblem of increased cost of facility and equipment as well as cost ofmanufacture.

In an attempt to solve the above described problem, the Japanese PatentApplication No. Hei 11-182264, for example, proposes a fasteningstructure of link and pin, in which a retaining ring 36 is employed.Specifically, as shown in FIG. 9, an annular space 45 is formed betweena circumferential edge of an opening of pin insertion holes 41 b, 42 bof the links 31, 32 and a corresponding end portion of a pin 33. Theretaining ring 36 is disposed in this space 45, thereby preventing therelative, disengaging movement of the pin 33 toward the side away fromthe opening. In this case, there is formed a tapered inner surface 43having a diameter gradually increasing from the pin insertion hole 41 btoward outside, surrounding the opening of the pin insertion hole 41 b.On the other hand, the pin 33 is formed with a tapered outer surface 44facing the tapered inner surface 43. A slanting angle of the taperedouter surface 44, with respect to the axis, is slightly smaller than aslanting angle of the tapered inner surface 7. With this arrangement,the tapered surfaces 43, 44 are farther away from each other in theoutward direction. The retaining ring 36 is made of an annular elasticmetal having a circular section, with a part of the ring cut out so thatthe ring can elastically spread and shrink in diameter.

However, the above described fastening structure between link and pin ofa crawler belt has the following problems resulting from that theopening portion of the pin insertion hole 41 b of the link 31 and theouter end portion of the pin 33 are tapered surfaces 43, 44respectively, and that the retaining ring 36 has a circular section.Specifically, first, assembling operation is costly. More specifically,since the section of the retaining ring 36 is circular, the ringcircumferential surface cannot have a sufficient area of contact witheach of the tapered surfaces 43, 44, being unable to obtain sufficientinitial friction from the elastic restoring force of the retaining ring36 alone. For this reason, in an assembling step, an operation ofdriving the retaining ring 36 inwardly is necessary. For this particularoperation of driving the retaining ring 36, a special jig dedicated tothe pressing operation must be prepared. Further, a pressing apparatuscapable of providing a necessary level of driving force is necessary. Asa result of these, a high cost is required for the assembling operation.

Secondly, in order to achieve a desired friction as after theassembling, the tapered inner surface 43 and the tapered outer surface44 have to be machined to a high accuracy. Specifically, if the anglemade by the two tapered surfaces 43, 44 is too large, the retaining ring36 cannot be held by the friction and moves away, becoming unable toprovide the expected function. For example, in the state shown in FIG.9, it has been confirmed that the angle θ between the tapered surfaces43, 44 must be smaller than 20° approximately. As a result of such ahigh machining accuracy required of each part, manufacturing cost ofthese has to increase.

The present invention is made to solve the above described problems,with an object to provide a fastening structure between link and pin ofa crawler belt which can be assembled by simple operation at a low cost,without requiring a high machining accuracy, and thus can bemanufactured at a low cost.

DISCLOSURE OF THE INVENTION

Now, a fastening structure of link and pin of a crawler belt accordingto a first invention is a fastening structure of a link and a pin in acrawler belt of a vehicle. An annular space 15 is formed between acircumferential edge of an opening of a pin insertion hole 5 of a link 2and an outer end portion of a pin 1 to be inserted in the pin insertionhole 5, and a retaining ring 3 is disposed in the space 15 wherebypreventing relative, disengaging movement of the pin 1 toward a sideaway from the opening. The structure is characterized in that one of thecircumferential edge of the opening of the pin insertion hole 5 of thelink 2 and the outer end portion of the pin 1 is formed with a taperedpressure receiving surface 8 having a diameter gradually decreasing inan axially inward direction, the other is formed with a pressing portion7, and the retaining ring 3 is formed with a friction surface 9 to bepress-contacted to the pressure receiving surface 8 by a force from thepressing portion 7 upon development of the relative movement in thedisengaging direction. It should be noted here that the pressing portion7 may be an edge portion as in the first embodiment through the thirdembodiment, or may be a tapered pressure receiving surface as in thefourth embodiment. In this case, a portion of the retaining ring 3contacted by the pressing portion 7, (a pressed surface), is formed as afriction surface as in the fourth embodiment.

According to the fastening structure between link and pin of a crawlerbelt provided by the first invention, the following function isperformed. First, if the pin 1 makes a relative movement in thedisengaging direction toward the side away from the opening, then thepressing portion 7 of the link 2 contacts the pressed surface 10 of theretaining ring 3, and the friction surface 9 of the retaining ring 3press-contacts the tapered, pressure receiving surface 8. Under thisstate, the ring 3 is under a force acting in the disengaging direction.This force F₁ can be divided into a component force F₂ acting verticallyto the pressure receiving surface 8 and another component force F₃acting along the pressure receiving surface 8. Based on this, therelative, disengaging movement toward the side away from the opening isprevented by selecting a condition that makes friction generated by thecomponent force F₂ acting vertically to the pressure receiving surface 8greater than the component force F₃ acting along the pressure receivingsurface 8. Specifically, the pressure receiving surface 8 slantedaxially inward is given a slant angle α that satisfies the abovementioned relationship μ·F₂>F₃ (where μ represents frictioncoefficient), thereby preventing the pin from relative, disengagingmovement out of the link toward the side away from the opening.

According to the fastening structure of link and pin of a crawler beltprovided by the first invention, the retaining ring 3 contacts thepressure receiving surface 8 via its friction surface 9. For thisreason, the retaining ring 3 has a greater area of contact with thepressure receiving surface 8 than in the prior art. Therefore, elasticrestoring force of the retaining ring 3 alone can generate sufficientinitial friction. Thus, there no longer is the need for the operation ofinwardly driving the retaining ring 3 during the assembly. As a result,there no longer is the need for the special jig and the pressingapparatus for driving the ring 3, and as a result, it becomes possibleto reduce cost necessary for the assembling operation.

Further, the slant angle α of the pressure receiving surface 8 slantingaxially inward should only satisfy the above mentioned relationshipμ·F₂>F₃. Thus, there no longer is the need for high machining accuracyin the angle of the tapered surface as is in the prior art, andtherefore it becomes possible to reduce relevant manufacturing cost.

A fastening structure between link and pin of a crawler belt accordingto a second invention is characterized in that the retaining ring 3includes a pressed surface 10 contacted by the pressing portion 7, andthe friction surface 9, whereas the pressed surface 10 and the frictionsurface 9 are farther away from each other in an outward direction.

According to the fastening structure between link and pin of a crawlerbelt provided by the second invention, the friction surface 9 and thepressed surface 10 of the retaining ring 3 are farther away from eachother in the outward direction. Therefore, even if there isinconsistency in an engaging dimension between the pressing portion 7and the pressure receiving surface 8 resulting from machining error,assembling error and so on, the friction surface 9 and the pressedsurface 10 of the retaining ring 3 can make respective engagements atvarious dimensions, which means an engageable range for the two isincreased. As a result, it becomes possible to allow for more generoustolerance in the shape and dimensions of the pressing portion 7 in thelink 2 and of the pressure receiving surface 8 in the pin 1 than in theprior art.

A fastening structure between link and pin of a crawler belt accordingto a third invention is characterized in that the retaining ring 3 has asquare section.

According to the fastening structure between link and pin of a crawlerbelt provided by the third invention, since the retaining ring 3 has asquare section, manufacture thereof becomes easy, and can be embodied ata low cost.

A fastening structure between link and pin of a crawler belt accordingto a fourth invention is characterized in that the pressing portion 7 isformed like an edge.

According to the fastening structure between link and pin of a crawlerbelt provided by the fourth invention, by making one of thecircumferential edge of the opening of the pin insertion hole 5 of thelink 2 and the outer end portion of the pin 1 as the edge-like pressingportion 7, it becomes possible to allow for even more generous tolerancein the shape and dimensions of the pressing portion 7 in the link 2 andof the pressure receiving surface 8 in the pin 1 than in the case whereboth are made as tapered pressure receiving surfaces.

A fastening structure between link and pin of a crawler belt accordingto a fifth invention is a fastening structure of a link and a pin in acrawler belt of a vehicle. An annular space is formed between acircumferential edge of an opening of a pin insertion hole 5 of a link 2and an outer end portion of a pin 1 inserted in the pin insertion hole5, and a retaining ring 3 is disposed in the space 15 whereby preventingrelative disengaging movement of the pin 1 toward a side away from theopening. The structure is characterized in that one of thecircumferential edge of the opening of the pin insertion hole 5 of thelink 2 and the end portion of the pin 1 is formed with a taperedpressure receiving surface 8 having a diameter gradually decreasing inan axially inward direction, the other is formed with an edge-likepressing portion 7, and the retaining ring 3 press-contacts each of thepressing portion 7 and the pressure receiving surface 8.

According to the fastening structure between link and pin of a crawlerbelt provided by the fifth invention, the following function isperformed. First, in an assembling step, when the retaining ring 3 isdisposed in the space 15 and the retaining ring 3 is pushed inward, thenthe edge-like pressing portion 7 is press-contacted to the retainingring 3 whereas the retaining ring 3 is press-contacted to the taperedpressure receiving surface 8. Under this state, a vicinity of thecontacting portion in the retaining ring 3 is elastically deformed bythe pressure, providing a surface on the retaining ring 3 on the sidefacing the pressure receiving surface 8. In other words, a frictionsurface 9 contacting the pressure receiving surface 8 is created.Therefore, if the pin 1 tends to make relative movement in thedisengaging direction toward the side away from the opening under thisstate, then the retaining ring 3 comes under a force F₁ acting in thedisengaging direction. This force F₁ can be divided into a componentforce F₂ acting vertically to the pressure receiving surface 8 andanother component force F₃ acting along the pressure receiving surface8. Based on this, the relative, disengaging movement of the pin towardthe side away from the opening is prevented by selecting a conditionthat makes friction generated by the component force F₂ actingvertically to the pressure receiving surface 8 greater than thecomponent force F₃ acting along the pressure receiving surface 8.Specifically, the pressure receiving surface 8 slanted axially inward isgiven a slant angle α that satisfies the above mentioned relationshipμ·F₂>F₃ (where μ represents friction coefficient), thereby preventingthe pin from relative, disengaging movement out of the link toward theside away from the opening.

According to the above described fastening structure between link andpin of a crawler belt provided by the fifth invention, the retainingring 3 has the friction surface 9 provided by the assemblage, makingcontact with the pressure receiving surface 8. Therefore, the retainingring 3 has a greater area of contact with the pressure receiving surface8 than in the prior art, making possible to obtain sufficient initialfriction. Further, since one of the circumferential edge of the openingof the pin insertion hole 5 of the link 2 and the outer end portion ofthe pin 1 is made into the edge-like pressing portion 7, the retainingring 3 receives the pressure at a point, and thus it becomes possible toperform the assembling operation more easily, using less pressing forcethan in the case where the two members are each formed with a taperedsurface, i.e. than in the case where the pressure is received on asurface. As a result, operating efficiency in the assembling operationcan be improved.

Further, the slant angle α of the pressure receiving surface 8 slantingaxially inward should only satisfy the above mentioned relationshipμ·F₂>F₃. Thus, there no longer is the need for high machining accuracyin the angle of the tapered surface as is in the prior art, andtherefore it becomes possible to reduce relevant manufacturing cost.Further, since one of the link 2 and the pin has the edge-like pressingportion 7, it becomes possible to allow for more generous tolerance inthe shape and dimensions of the link 2 and of the pin 1 than in the casewhere both are made as tapered pressure receiving surfaces.

A fastening structure between link and pin of a crawler belt accordingto a sixth invention is characterized in that the retaining ring 3 has acircular section.

According to the fastening structure between link and pin of a crawlerbelt of the sixth invention, since the retaining ring 3 has a circularsection, manufacture thereof becomes easy, making possible to embody ata low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged sectional view showing a principal portion of afirst embodiment of a fastening structure of link and pin of a crawlerbelt according to the present invention.

FIG. 2 is an enlarged sectional view of a principal portion, showing anoperating state of the above embodiment.

FIG. 3 is an enlarged sectional view showing a principal portion of asecond embodiment.

FIG. 4 is an enlarged sectional view showing a principal portion of athird embodiment.

FIG. 5A is an enlarged sectional view of a principal portion fordescribing a state of assembly in the third embodiment.

FIG. 5B is an enlarged sectional view of a principal portion fordescribing another state of assembly in the third embodiment.

FIG. 6 is an enlarged sectional view showing a principal portion of afourth embodiment.

FIG. 7A is an enlarged sectional view of a principal portion showing astate before assembly in a fifth embodiment.

FIG. 7B is an enlarged sectional view of a principal portion showing astate after assembly in the fifth embodiment.

FIG. 8 is a sectional view showing an example of a fastening structureof a link and a pin of a crawler belt in a prior art crawler belt linkchain.

FIG. 9 is an enlarged sectional view showing a principal portion of theprior art.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, specific embodiments of the fastening structure of link and pin ofa crawler belt according to the present invention will be described indetail with reference to the accompanying figures. First, the retainingmechanism itself is exactly the same as the prior art shown in FIG. 8and FIG. 9, comprising a pin 1, a link 2 and a retaining ring 3.Therefore, the description to be given here below will primarily focuson characteristic points.

First, as shown in FIG. 1, the pin 1 has an end, close to which acircumferential groove 4 having a generally triangular section isformed. Further, the link 2 is formed with a pin insertion hole 5 intowhich the pin 1 is press-fitted. The pin insertion hole 5 has anopening, around which an annular recess 6 is formed. The groove 4 of thepin 1 and the recess 6 of the pin insertion hole 5 form an annularfitting space 15 recessing axially inward and having an annular opening,between a circumferential edge of the opening of the pin insertion hole5 and the outer end portion of the pin 1. The recess 6 meets an edge ofthe opening of the pin insertion hole 5. This edge serves as a pressingportion 7, function of which will be described later. The groove 4 ofthe pin 1 includes a tapered outer surface 8 facing the pressing portion7. The tapered outer surface 8 gradually shrinks in diameter axiallyinwardly, and as will be described later, serves as a pressure receivingsurface. The retaining ring 3 is made of an annular elastic metal, witha part of the ring cut out so that the ring can elastically spread andshrink in diameter. Further, the retaining ring 3 has a generally squaresection, with one corner of the square being in an inner diameter region(the lower side as in the figure) and another corner being in an outerdiameter region (the upper side as in the figure).

According to the above described fastening structure between link andpin of a crawler belt, assembling operation can be completed by simplypress-fitting the pin 1 into the pin insertion hole 5 of the link 2,then spreading and disposing the retaining ring 3 into the groove 4 ofthe pin 1, and finally removing the spreading force thereby allowing theretaining ring 3 to elastically shrink in diameter. Under this state,the retaining ring 3 has its inner diameter side contacting the taperedouter surface 8 whereas the outer diameter side has its inner sidesurface contacting the pressing portion 7. Hereinafter, in the retainingring 3, the surface contacting the tapered outer surface 8 (i.e. theouter side surface on the inner diameter side) will be called a frictionsurface 9, and the surface contacting the pressing portion 7 (i.e. theinner side surface on the outer diameter side) will be called a pressedsurface 10.

Under the state of assembly as described above, if the link 2 tends tomove out of the pin 1, the following function prevents the disengagingmovement. Specifically, first, if the link 2 tends to move rightward asin FIG. 1 (i.e. if the pin 1 tends to make a relative movement in adisengaging direction toward the side away from the opening), then thepressing portion 7 of the link 2 presses the pressed surface 10 of theretaining ring 3, twisting the retaining ring 3 outward as shown in FIG.2, thereby making the friction surface 9 of the retaining ring 3 contactthe tapered outer surface, i.e. the pressure receiving surface 8. Underthis state, the ring 3 is under a force acting in the disengagingdirection (to the right as in the figure). This force F₁ can be dividedinto a component force F₂ acting vertically to the pressure receivingsurface 8 and another component force F₃ acting along the pressurereceiving 8. If the friction generated by the component force F₂ actingvertically to the pressure receiving surface 8 is greater than thecomponent force F₃ acting along the pressure receiving surface 8, thenthe relative, disengaging movement of the pin 1 toward the side awayfrom the opening is prevented. For this purpose, the pressure receivingsurface 8 slanted axially inward is given a slant angle α that satisfiesthe above mentioned relationship μ·F₂>F₃ (where μ represents frictioncoefficient).

According to the fastening structure of link and pin of a crawler beltdescribed above, the retaining ring 3 contacts the pressure receivingsurface 8 via its friction surface 9. For this reason, the retainingring 3 has a greater area of contact with the pressure receiving surface8 than in the prior art. Therefore, elastic restoring force of theretaining ring 3 alone can generate sufficient initial friction. Thus,there no longer is the need for the operation of inwardly driving theretaining ring 3 during the assembly. As a result, there no longer isthe need for the specialized jig and the pressing apparatus for drivingthe retaining ring 3, and as a result, it becomes possible to reducecost necessary for the assembling operation. Further, the shape of thepressing portion 7 and the pressure receiving surface 8, and materialcharacteristic of the retaining ring 3 are so selected that even if thepin 1 and the link 2 are disassembled for a purpose of repair and so on,the retaining ring 3 can be reused since the retaining ring 3 is onlyelastically deformed at the time of the assembly.

Further, the slant angle α of the pressure receiving surface 8 slantingaxially inward should only satisfy the above mentioned relationshipμ·F₂>F₃. Thus, there no longer is the need for high machining accuracyin the angle of the tapered surface as is in the prior art, andtherefore it becomes possible to reduce relevant manufacturing cost.Further, the edge-like pressing portion 7 provided in the line 2 makespossible to allow for more generous tolerance in the shape anddimensions of the pressing portion 7 in the link 2 and of the pressurereceiving surface 8 in the pin 1 than in the case where both are made astapered pressure receiving surfaces.

Further, according to the prior art fastening structure of link and pin,the tapered surface 44 must be formed also in the link 2. However, sincethe link 2 has a non-circular outer shape, it is very difficult to forma tapered annular surface 44 in such an object as the link 2. On thecontrary, according to the embodiment described above, the link 2 shouldonly be formed with the pressing portion 7, and there is no need forforming the tapered surface. This leads to an advantage of simplifiedmachining operation.

FIG. 3 shows a second embodiment, in which the retaining ring 3 has asquare section like the embodiment shown in FIG. 1. The differencehowever, is that the shape of a vicinity of the pressing portion 7 inthe link 2 changed. Specifically, a tapered guide surface 11 having adiameter decreasing in an axially inward direction is formed on anoutward side of the pressing portion 7. At the time of assembly, theguide surface 11 allows the pressed surface 10 of the retaining ring 3to reliably contact the pressing portion 7, thereby making easy theassembling operation of the retaining ring 3. According to thisembodiment, again, the same function and effect as achieved in the firstembodiment can be obtained.

FIG. 4 shows a third embodiment, in which the retaining ring 3 has adifferent shape in section. In this case, the section is not square asin the embodiments in FIG. 1 and FIG. 2 (in which the friction surface 9and the pressed surface 10 are parallel to each other). Instead, thefriction surface 9 and the pressing surface 10 are each tapered to havean outwardly increasing diameter, and further, a distance between thetwo surfaces increases in the outward direction. It should be noted herethat the retaining ring 3 is given a laterally mirror symmetric sectionin the figure, so that the ring can be used also at the other endportion of the pin 1.

Again, according to this fastening structure of link and pin of acrawler belt provided by the third embodiment, the same function andeffect as achieved in the above can be obtained. In addition, there isanother advantage in that even more generous tolerance can be allowedfor in the shape and dimensions of the pressing portion 7 in the link 2and of the pressure receiving surface 8 in the pin 1 than in the abovedescribed embodiments. Specifically, since the friction surface 9 andthe pressed surface 10 of the retaining ring 3 are disposed in anoutwardly opening taper pattern, as shown in FIG. 5A and FIG. 5B, theretaining ring 3 can now make engagement between the pressing portion 7and the pressure receiving surface 8 not only at a place closer to theopening of the space 15 (FIG. 5A) but also at a place farther from theopening (FIG. 5B), making possible to prevent relative movement of thepin 1 in the disengaging direction. In other words, even if there isinconsistency in engaging dimension between the pressing portion 7 andthe pressure receiving surface 8 resulting from machining error,assembling error and so on, the friction surface 9 and the pressedsurface 10 of the retaining ring 3 are not limited in a certain fixedengaging dimension, and therefore can make respective engagements atvarious dimensions. This means an engagable range for the two surfacesis increased.

FIG. 6 shows a fourth embodiment. In this embodiment, the retaining ring3 has the same sectional shape as in FIG. 4 and FIG. 5, whereas thepressing portion 7 of the link 2 is made as a tapered, pressurereceiving surface having a diameter gradually decreasing in an axiallyinward direction. Specifically, in this case, a pin insertion hole 5also is formed with a pressure receiving surface 7 around the opening,in addition to the pressure receiving surface 8 formed at the outer endportion of the pin 1. With this arrangement, a distance between thepressure receiving surfaces 7, 8 gradually increases outwardly.According to this embodiment, a pressed surface 10 of the retaining ring3 serves as a friction surface, i.e. both of the friction surfaces 9, 10make contact with the pressure receiving surfaces 7, 8 respectively.Such a structure as the above brings about the functions and effectsdescribed earlier, and in addition, it becomes possible to furtherreliably prevent the relative movement of the pin 1 in the disengagingdirection since the retaining ring 3 now has even more increased area ofcontact. It should be noted here that in this case again, the retainingring 3 is given a laterally mirror symmetric section as in the figure,so that the ring can be used also at the opposite end portion of the pin1.

FIG. 7A and FIG. 7B show a fifth embodiment, in which the retaining ring3 is made to have a circular section. Hereinafter, detailed descriptionwill be made with reference to FIG. 7A and FIG. 7B. Referring first toFIG. 7A, the pin 1 has an end, close to which a circumferential groove 4having a generally triangular section is formed. Further, the link 2 isformed with a pin insertion hole 5 into which the pin 1 is press-fitted.The pin insertion hole 5 has an opening, around which an annular recess6 is formed. The groove 4 of the pin 1 and the recess 6 of the pininsertion hole 5 form an annular fitting space 15 recessing axiallyinward and having an annular opening, between a circumferential edge ofthe opening of the pin insertion hole 5 and the outer end portion of thepin 1. Further, an edge-like pressing portion 7 is formed at a locationwhere the recess 6 meets the opening of the pin insertion hole 5,further outward of which, starting from the pressing portion 7 in anoutward direction, there is formed an axially slanted, tapered guidesurf ace 11 gradually increasing in diameter. The groove 4 of the pin 1has a tapered outer surface 8 facing the pressing portion 7. The taperedouter surface 8 gradually increases in diameter in the axially outwarddirection, and as will be described later, serves as a pressurereceiving surface. With this arrangement, the tapered outer surface(hereinafter called a pressure receiving surface 8) has a slantingangle, slanting with respect to the axis, smaller than a slanting angleof the guide surface 11. On the other hand, the retaining ring 3 is madeof an annular elastic metal, with a part of the ring cut out so that thering can elastically spread and shrink in diameter. Further, theretaining ring 3 has a generally circular section, being press-contactedto the pressing portion 7 and the pressure receiving surface 8 in theabove mentioned space 15.

With the above-described fastening structure between link and pin of acrawler belt, assembling operation involves press-fitting the pin 1 intothe pin insertion hole 5 of the link 2, then spreading and disposing theretaining ring 3 into the groove 4 of the pin 1, and then removing thespreading force thereby allowing the retaining ring 3 to elasticallyshrink in diameter. Thereafter, the retaining ring 3 is pushed inwardlyinto the space 15 to complete the assembly. Under this state shown inFIG. 7B, the retaining ring 3 has its outer diameter sidepress-contacted by the edge-like pressing portion 7 whereas the innerdiameter portion press-contacted by the tapered pressure receivingsurface 8. Under this state, a vicinity of the press-contacted portionin the retaining ring 3 is elastically deformed by the pressure,providing a surface on the retaining ring 3, on the side facing thepressure receiving surface 8. In other words, a friction surface 9contacting the pressure receiving surface 8 is created.

Under the state of assembly as described above, if the link 2 tends tomove out of the pin 1, the following function controls the disengagingmovement. Specifically, under the sate where the pressing portion 7 ofthe link 2 press-contacts the retaining ring 3 and the friction surface9 of the retaining ring 3 press-contacts the pressure receiving surface8 of the pin 1, if the link 2 tends to move rightward as in FIG. 7 (i.e.if the pin 1 tends to make a relative movement in the disengagingdirection toward the side away from the opening), then the retainingring 3 comes under a force acting toward the disengaging direction (tothe right as in the figure). This force F₁ can be divided into acomponent force F₂ acting vertically to the pressure receiving surface 8and another component force F₃ acting along the pressure receiving 8. Ifthe friction generated by the component force F₂ acting vertically tothe pressure receiving surface 8 is greater than the component force F₃acting along the pressure receiving surface 8, then the relativedisengaging movement of the pin toward the side away from the opening isprevented. Therefore, according to this embodiment, the pressurereceiving surface 8 slanted axially inward is given a slant angle α thatsatisfies the above mentioned relationship μ·F₂>F₃ (where μ representsfriction coefficient).

According to the above described fastening structure between link andpin of a crawler belt, the friction surface 9 of the retaining ring 3provided by the assemblage makes contact with the pressure receivingsurface 8. Therefore, the retaining ring 3 has a greater area of contactwith the pressure receiving surface 8 than in the prior art, makingpossible to obtain sufficient initial friction. Further, since theretaining ring 3 receives the pressure at a point, it becomes possibleto perform the assembling operation more easily, using less pressingforce than in the case where the two members are each formed with atapered surface, i.e. than in the case where the pressure is received ona surface. As a result, operating efficiency in the assembling operationcan be improved. Further, the shape of the pressing portion 7 and thepressure receiving surface 8 and material characteristic of theretaining ring 3 are so selected that even if the pin 1 and the link 2are disassembled for a purpose of repair and so on, the retaining ring 3can be reused since the retaining ring 3 is only elastically deformed atthe time of the assembly.

Further, the slant angle α of the pressure receiving surface 8 slantingaxially inward should only satisfy the above mentioned relationshipμ·F₂>F₃. Thus, there no longer is the need for high machining accuracyin the angle of the tapered surface as is in the prior art, andtherefore it becomes possible to reduce relevant manufacturing cost.Further, the edge-like pressing portion 7 in the link 2 according to thepresent embodiment makes possible to allow for more generous tolerancein the shape and dimensions of the pressing portion 7 in the link 2 andof the pressure receiving surface 7 in the pin 1 than in the case whereboth are made as tapered pressure receiving surfaces.

Further, according to the prior art fastening structure of link and pin,the tapered surface 44 must be formed also in the link 2. However, sincethe link 2 has a non-circular outer shape, it is very difficult to forma tapered annular surface 44 in such an object as the link 2. On thecontrary, according to the embodiment described above, the link 2 shouldonly be formed with the edge-like pressing portion 7, and there is noneed for forming the tapered surface. This leads to an advantage ofsimplified machining operation.

Embodiments of the fastening structure between link and pin of a crawlerbelt according to the present invention being described thus far, thefastening structure between link and pin of a crawler belt according tothe present invention is not limited to those described in theembodiments, but can be varied in many ways. For example, according tothe embodiments, the pressure receiving surface 9 is formed in the pin 1and the pressing portion 7 is formed in the link 2. Conversely, however,the pressing portion 7 may be formed in the pin 1 and the pressurereceiving surface 9 may be formed in the link 2. Further, the sectionalshape of the retaining ring 2 is preferably mirror symmetric as in theabove embodiments, for usability at either end of the pin 1. However,the shape may not be mirror symmetric depending on a situation, thoughthe square or circular section as in FIG. 1, FIG. 3 or FIG. 7 bringsabout such advantages as easiness in manufacture and low cost inapplication.

What is claimed is:
 1. A fastening structure of link and pin of avehicle crawler belt, wherein an annular space (15) being formed betweena circumferential edge of an opening of a pin insertion hole (5) of alink (2) and an outer end portion of a pin (1) to be inserted in the pininsertion hole (5), a retaining ring (3) being disposed in the space(15) whereby preventing relative, disengaging movement of the pin (1)toward a side away from the opening; characterized in that one of thecircumferential edge of the opening of the pin insertion hole (5) of thelink (2) and the outer end portion of the pin (1) is formed with atapered pressure receiving surface (8) having a diameter graduallydecreasing in an axially inward direction, the other being formed with apressing portion (7), and the retaining ring (3) being formed with afriction surface (9) to be press-contacted to the pressure receivingsurface (8) by a force from the pressing portion (7) upon development ofthe relative movement in the disengaging direction.
 2. The fasteningstructure of link and pin of a vehicle crawler belt according to claim1, characterized in that the retaining ring (3) includes a pressedsurface (10) contacted by the pressing portion (7), and the frictionsurface (9); the pressed surface (10) and the friction surface (9) beingfarther away from each other in an outward direction.
 3. The fasteningstructure of link and pin of a vehicle crawler belt according to claim 1or claim 2, characterized in that the retaining ring (3) has a squaresection.
 4. The fastening structure of link and pin of a vehicle crawlerbelt according to claim 1 or claim 2, characterized in that the pressingportion (7) is an edge.
 5. A fastening structure of link and pin of avehicle crawler belt, wherein an annular space (15) being formed betweena circumferential edge of an opening of a pin insertion hole (5) of alink (2) and an outer end portion of a pin (1) to be inserted in the pininsertion hole (5); a retaining ring (3) being disposed in the space(15) whereby preventing relative disengaging movement of the pin (1)toward a side away from the opening; characterized in that one of thecircumferential edge of the opening of the pin insertion hole (5) of thelink (2) and the end portion of the pin (1) is formed with a pressurereceiving surface (8) having a diameter gradually decreasing in anaxially inward direction, the other being formed with an edge-likepressing portion (7), and the retaining ring (3) press-contacting eachof the pressing portion (7) and to the pressure receiving surface (8).6. The fastening structure of link and pin of a vehicle crawler beltaccording to claim 5, characterized in that the retaining ring (3) has acircular section.